Arc lamp



June 16, 1931. o. F. SPAHR 1,810,299

ARC LAMP Filed May 23, 1927 3 Sheets-Sheet 1 June 16, 1931. SPAHR 1,810,299

ARC LAMP Filed May 23, 1927 3 Sheets-Sheet 2 June 16, 1931. SPAHR 1,810,299

ARC LAMP I Filed May 2:, 1927 3 Sheets-Sheet s Patented June 16, 1931 UNITED STATES PATENT OFFICE ORAL F. SPAI-IR, OF CHICAGO, ILLINOIS, ASSIGNOR TO ENTERPRISE OPTICAL MFG. 00., OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS ARC LAMP Application filed May 23, 1927. Serial No. 193,433.

My present invention relates to an improvement in arc lamps of the reflecting type and is particularly adapted for use in motion picture projecting apparatus, although it may have ageneral application.

One of the objects of the invention is to provide an electric arc lamp with a combined arc striker and are crater position indicator.

Another object of the invention is to provide for motion picture projecting apparatus an, improved and eflicient means for predetermining the adjustment of the projecting light rays and maintaining such adjustment.

Other objects of the invention will appear hereinafter, the novel features and combinations being set forth in the appended claims.

For the purpose of illustrating the salient features of the invention, I have shown my improvement embodied in a reflecting arc g0 lamp known to the trade as the motiograph reflecting arc lamp and the accompanying drawings illustrate such embodiment.

In said drawings Fig. 1 is an elevation of an arc lamp of a motion picture projecting apparatus with the cover removed and showing my improvement applied thereto;

Fig. 2 is an enlarged view in elevation of the reflector holder with my improvement in its proper position relative thereto;

Fig. 3 is a View in cross section through the lamp structure showing the reflector holder in front elevation with my improvement applied thereto; and

Fig. 4 is an enlarged detailed view taken on the line 44 of Fig. 3, lookingin the direction of the arrows.

In the accompanying drawings, I have shown a lamp structure with the cover or housing therefor removed. The projecting head 5 is of usual construction for the mounting of the lenses. The projecting head 5is supported on the base frame 6 at the forward end thereof in position to permit the reflector v 7 to direct the light rays therethrough from the are between the ends of the carbons 8 and 9. The reflector 7 is adj ustably mounted so that it may be slid longitudinally along the frame 6 by means of a hand wheel 10 on the rod 11. By referring to Fig.3, it will be seen that the reflector is mounted on the auxiliary frame 42 and that the latter is in turn mounted to slide along the rods 17 and 18. By referring to Fig. 1, it will be seen that rotation of'the rod 11 will rotate the screw threads 43 which extend through the frame 42 on which the reflector is directly mounted. After the reflector has been adjusted to the desired position, it may be secured in adjusted position by means of the set screws 44, 44 shown in Fig. 2, these set screws engaging the fixed guide rod 18.

The carbon 9 projects from the holder 13 through the center of the reflector 7 so that its forward end will be located at the focal center of the reflector. The carbon holder 13 may be adjusted in elevation by means of the hand wheel 16 which rotates the rod 14 and in turn operates the elevating mechanism. It should be understood that there is another rod directly back of the rod 14 with the actuating wheel thereon, this structure being for the purpose of operating the mechanism for tilting the carbon holder sidewise.

The hand wheel 45is connected to a ro- T5 tatable rod 15 which, when rotated, operates mechanism for tilting the reflector 7 on the axis 46. Another rod is rotated directly back of the rod 15 with another actuating hand wheel thereon and this structure is connected to mechanism for swinging the reflector on a vertical axis shown at 47 in Fig. 3. By referring to Figs. 1 and 3, itis seen that the mechanism for swinging the reflector on the axis 46 is applied at 48. By referring to Figs. 2 and 3, it will be seen that the mechanism for swinging the reflector on a vertical axis is shown at 49. The actuating rod for adjusting the reflector on the vertical axis is shown at 15' in Fig. 2. It will be seen that the reflector is swung positively in one direction and moved in the opposite direction by the spring 50.

The carbon holders 1.2 and 13 are mounted on supports 51 and 52 which fit on and slide along the track 53 which. is secured at its end to the frame 6. Mounted beneath the track 53 is a rod 54 which is provided with right hand and left hand screw threads 55 and 56, which respectively engage screw-threaded 100 brackets 57 and 58 on the supports 51 and 52. Therefore, when the rod 54 is rotated by means of the wheel 59, the carbons may be moved toward and from each other.

lVith the foregoing description of the wellknown are lamp structure of moving picture projecting appz'zratus, known in the trade as motiograph projecting arc lamp, it is believed that the application of my improvements thereto will be fully understood. In other .vords, it is belie/"ed that the illustration in the drawings is su'll'icient to show the well-known mechanism for mounting and adjusting the reflector on vertical and horizontal axes, sliding; it along; the frame, lifting and lowering the rear carbon 9 and adjusting it laterally and moving the carbons toward and from each other so that when they contact at their ends, the arc will be in proper position with respect to the reflector and with respect to the lens holder In combining); my improvement with the structure above described and shown in the drawings, I provide a split sleeve 19 adapted to adjustably fit on the rod 18 and be securely clamped thereto in adjusted position by means of the clamping; screw which extends through the clamping jaws 61, as shown in 3. The sleeve 19 carries a bracket 20 which is elongated, as shown in Fig. 2, so to afford spaced-apart bearings 21 and 25 for the rock shaft In other words, the bracket 20 is slidablv mounted on the fixco rod 18 and integral with this bracket is a clamping; sleeve 19 as to secure the bracket 20 in adjusted position on the rod 18.

On the rock shaft 22 is secured a collar 23 by means of a set screw 2 1, as shown in Fig. 2. The left hand end of the roc shaft 22 is rigidly secured at 62 to the arc stri lever It will thus be seen that the hearing will prevent longitudinal movement of the rock shaft 22 in one direction and the collar 23 by abutting against the bearing 21 will prevent the rock shaft from moving longitudinally in the other direction.

A universal joint 27 connects the r ck shaft to an actuati shaft 28, which. as shown in Fig. 1, is adapted to be operated by a hand wheel. 29. VVl en the hand waeel 29 is rotated the lever 26 may be swung in an are on the axis of the rock shaft wnile beinp' supported by the bearings 21 and 25 which in turn are supporte by the bracket secured in adjusted position to the fixed and stationary rod 18. The are striker comprises 'tl e arm 26 and the mechanism mounted thereon for carrying the short carbon 38 into a iiredetermined relation with the ends of the carbons 8 and 9 so as to connect the latter and start the are between the ends of the carbons 8 and 9 after which the are striker carbon 38 may be withdrawn to its dotted line position shown in Fig. 3.

The arm 26 is preferably a plate or strip of metal and is extended upwardly from the rock shaft 22 to a position near the carbons 8 and 9. The arm 26 has seemed thereto a plate or strip 33 by means of the set screws 35, 35 and at the outer end of the plate or strip is mounted the arms 36 and 37 to constitute clamps for holding the arc striker carbon 38 securely in adjusted position. The clamping arms 36 and 3'? may be drawn together against the arc strikin carbon 38 by means of the set screws 39.

It should be understood that the arc striking: carbon 38 is insulated from the arm 26 so that when the carbon 38 connects the carbons 8 and 9 there will be no grounding of the electric current through the arm 28. For this purpose, a plate or strip of insulation is mounted between the arm 28 and the strip 33. As shown in Fi l, the set screw 35 is screw-threaded through the plate or strip 33 and the head of the set screw is insulated from the plate or strip 26 by means of an insulating washer 41. Therefore. the plate or strip 26 is electrically insulated from the plate or strip and the clamping abutments 36 and 37 which engage. and hold the are striking carbon 38.

t should be understood that the short are striking carbon 38 may be so adjusted between the jaw-like clamping members 39 and a? hat its tip may be presented in (,-en tered relation to the focal point of the reflector 7 when the arm 26 is at the limit of its forward position as shown in full lines in Fig. 3. Having once predetermined the correct focal point of the reflector 7, the arc striker may be secured in such adjusted position by clamping the sleeve 19 to the fixed and stationary rod 18 by means of the set screw 60. After that, the position of the carbon 38 Wlll always indicate the correct position of the crater between the ends of the lamp carbons 8 and 9. It should also be noted that such adjustment of the position of the are striking carbon is in harmony with the adjustments of the reflector including its adjustment along the rods 17 and 18. Such adjustment of the are striking carbon is also in harmony with the adjustments of the carbons 8 and 9 toward and from each other. It should, of course. be understood that during the operation of the motion picture projecting apparatus, well-known mechanism is being used to automatically feed the carbons 8 and 9 toward each other to maintain the are between the ends of the carbons. During the normal operation of the motion picture projecting apparatus, the are striking carbon 38 is in its rear position shown in but at any time the are striking carbon 33 may be n'loved toward the arc to serve as an indication where it should be located and the carbons 8 and 9 may be adjusted carefully. That is to say, not only does my improvement serve to strike the are between the ends beyond its are striking position. It will also mechanism, the arc may be brought back to the proper focus of the reflector.

Itshould also be noted that I provide automatic means for throwing the arc striker back to the dotted line position shown in Fig. 3 when the hand wheel 29 is released. For this purpose, a spring 31 acts on a pin 31 which engages the rear edge of the plate 26 above and near the axis of the rock shaft 22 as shown in Fig. 3.

movement of the arc striker when swung to its dotted line position by the spring 31 acting on the pin 31. It should be understood that the spring 31 is located in a recess in the bracket at the bottom of a hole which receives the pin 31.

When the operator of the arc striker grasps the handle 29 to swing the arc striking mech anism to the full line position thereof shown in Fig. 3, he is warned that the are striking 1 carbon is very close to its final position by the back of the plate 26 striking against an abutment 32 whichis mounted to slide in the upper portion of the bracket 20 and is provided with a stiff spring 32, as shown in Fig. 3. The spring 32 will assist the spring 31 to give the arc striker an initial impulse to throw it back toits dotted line position when the handle 29 is released. However, the main purpose of the yielding abutment 32 to offer appreciable resistance to further movement of the are striking carbon so that the operator may be warned that the are striking carbon is approximately in the desired position so that he may not cause the 1 carbon 38 to strike any severe blows against the ends of the carbons 8 and 9 and so that the operator may make observation of the ends of the carbons 8 and 9 just before the carbon 38 reaches its final position. This enables the operator to carefully adjust thepositions of the ends of the carbons 8 and 9 so that when the carbon 38 does reach its final position, the arc will be properly struck and continued after the handle 29 is released, and

\ the arc striker returns automatically to its initial position. 7

It will be seen that the yielding abutment 32 serves to limit the forward movement of the arc striker so that the carbon will not go be evident from the foregoing description that the short carbon 38 by being insulated from its holder serves to electrically connect the ends of the carbons 8 and 9 when brought to positions adjacent each other at the desired point where the arc should be, such desired point being indicated by the position which the carbon 38 assumes when it first en gages the yielding abutment 32.

It should also be noted that since the arm which carries the insulated carbon pencil 38 is pivoted as shown in Fig. 3, the yielding abutment 32 may serve not only as a signal to the operator that the carbon pencil 38 is near its limit of movement but by reason of i the strong spring 32 the arm may be automatically swung back past the dead center oft-he rock shaft 22 when the operating wheel 29 is released.

It will also be seen that the rear end of the carbon pencil 8 is intended to have the crater of the electric arc lamp so that it will face the reflector. The rear carbon pencil 9 is adjustable in elevation as well as laterally and longitudinally, and therefore the crater may be controlled. The adjusted position of the arc striker, however, also indicates the desired position of the crater at the focal point of the reflector. Therefore, when the arc striker is moved toward the longitudinal line extending through the carbons 8 and 9, the desired location of the crater is indicated and the carbon pencils 8 and 9 are adjusted accordingly. Therefore, when the arc is finally struck, the adjustments will be correct for the moving picture projecting apparatus including the beam of light which passes through the lenses. Of course, as soon as the arc is struck, the wheel 29 is released and the spring-pressed devices 31 and 32, shown in Fig. 3, will automatically swing the arc striker back to its initial position, as shown in dotted lines in Fig. 3, with the lower edge 63 of the arm 26 abutting against the limit stop 30.

Obviously those skilled in the art may make various changes in the details and arrange-- ment of parts without departing from the spirit and scope of the invention as defined by the claimshereto appended, and I wish therefore not to be restricted to the precise tween the ends of said pencils, and a yielding abutment for arresting the swinging movement of said are striker toward such predetermined location.

2. The combination with an electric are ice lamp, of a combined arc striker and crater position indicator for the carbon pencils of the lamp, means for operating said are striker and crater position indicator, and a yielding abutn'icnt for said combined arc striker and crate position indicator to serve as a signal. to the operator when said arc striker and indicator approaches its final position between the ends of the carbon pencils.

The combination with an electric arc O. lamp comprising carbon pencils, of a combined arc striker and crater position indi cater for said carbon pencils, said are striker and enter position indicator being adjustable longitudinally of one of said carbon pencils, means tor securing the arc striker and crater position indi-ator in adjusted position, and mechanism for operating said are striker and indicator.

4. In moving picture projecting apparatus comprising an arc lamp having adjustable carbon pencils, of an arc strik rcomprising a swinging arm having an i1 .sul ted carbon pencil. mounted thereon, manual means for swinging said arm to move the carbon perv. cil thereon into position tor connecting electrically the ends of the lamp carbon pencils to strike the are between the same, a springpressed device engaging said arm to swing the same automatically away from said lamp car 2011 pencils to initial position.

5. In moving picture projecting appilltltlitf, the combination with an electric arc lamp having a reflector adjustable on horizontal and vertical axes, carbon pencils adjustable toward and from each other with the rear carbon pencil also adjustable in elevation and laterally with respect to the crater in the rear of the "forward carbon pencil, which crater faces the reflector, of an arc striker and crater indicator comprising a swinging arm with an insulated carbon pencil mounted thereon, means for swinging said arm to move the carbon pencil thereon into a predetermined position for adjustment of the cra ter and for adjustment of the rear caroon pencil to e'tlect the striking of an are at the "(Focal point of the reflector.

(S. The combination with an electric arc lamp, of a combined crater position indicator and are striker for the carbon pencils ol the arc lamp, comprising; a pivoted arm with an insulated carbon pencil thereon, means for operating said combined crater position indicati and are striker by s vinging said arm, a yielding limit stop for said arm, and a spring acting on said limit stop to exert a spring-prcssed force on said arm to swing it automatically back toward initial position over and beyond the dead center of the pivotal point of said arm.

7.1a an arc lamp, the combination with carbon pencils, of means for adjusting the position of said carbon pencils, and mechanism operab e independently of the mecha nism for adjusting said carbon pencils to predetermine the location of the crater between the carbon pencils comprising a swinging arm having an insulated carbon pencil mounted thereon, manual means for swinngi' said arm to move the carbon pencil thereon into position for connecting electrically the ends oi the lamp carbon pencils to strike the arc between the same, and a spring-pressed device engaging said arm to swing the same automatically away from said lamp carbon pencils to initial position.

8. In an arc lamp for motion picture proj acting apparatus, carbon pencils for the arc lamp, a reflector for the arc lamp, means for adjusting the positions of said pencils, means for adjusting the position of said reflector, and means movable along a defined path from an inoperative initial position to a position in front of the reflector for predeterminiug the position of the crater between the carbon pencils and for strik ng an are between said pencils and means for moving said crater positioning means to compensate for movements of said reflector.

9. in an arc lamp for motion picture projecting apparatus, carbon pencils for the arc lamp, a reflector for the are lamp, means for adjusting the positions of said pencils, means for adjusting the position of said reflector, and means movable from an inoperative initial position in front of the reflector r'or predetermining the position of the crater between the carbon pencils and for striking an are between said pencils comprising an arm having a carbon pencil on the end thereof, a mounting for the arm longitudinally adjustable on the lamp, said arm being mounted to swing from its initial inoperative position into an operative position. means for swinging said arm from the end of the lamp, :1 spring-pressed device for resisting the swinging movement of the arm into an operative position, said spring-pressed device increasin g the resistance on said arm as the arm nears the limit of its swinging movement toward its operative position, and a stop for limiting the swinging movement of the arm into its operative position.

10. In an arc lamp having longitudinally and vertically adjustable carbon pencils and a longitudinally and angularly adjustable reflector, the combination of a combined crater position indicator and are striker mechanism. said mechanism being movable into an operative position in front of the reflector and ad justable in harmony with the adjustment of the carbon pencils.

11. In an arc lamp having longitudinally and vertically adjustable carbon pencils and a longitudinally and angularly adjustable rc flector, the combination of a combined crater position indicator and are striker llhl'llilllllliL said mechanism being movable into an operative position in front of the reflector and adjustable in harmony with the adjustment of the carbon pencils and also adjustable in harmony with the adjustments of the reflector.

In testimony whereof I have signed m name to this specification on this 20th day of May, A. D. 1927.

ORAL F. 'SPAHB. 

